at 3 weeks, you're most likely to have sore breasts and you might feel bloated (like you would just before a period). You won't know you're pregnant until you've missed a period and have gotten a positive pregnant test.
My boobs hurt so bad that I couldnt even sleep on my stomach anymore. :( I was also sick all the time. I didn't have as much enegery as all my friends had when we would go out at night and I was sleeping alot. I remember telling my fiance that out of all the times I "thought" I was pregnant...which was all the time. I was positive I was this time. We made a doctors appt. and it was confirmed. :) He is due Feb. 05 and I am so ready to meet my stud muffin!!